Assessing climate change-induced precipitation effects on the long-term reliability of common final landfill cover systems

A final landfill cover is a critical component of modern municipal solid waste (MSW) landfill design for reducing rainfall infiltration and ensuring long-term environmental protection. Climate-driven changes in precipitation may compromise cover performance, yet their implications throughout the entire service life of landfill covers remain poorly understood. This study aims to investigate the impact of climate change-induced precipitation on the serviceability of common landfill covers over a lifespan of 100 years. A new reliability-based assessment framework is developed, explicitly accounting for projected climate change and uncertainty in rainfall characteristics. The long-term failure probability of three common landfill covers is analysed for a semi-arid climate (Edmonton) and two humid climates (Shenzhen and Singapore). It is found that all three cover systems remain serviceable for at least 100 years in the examined climates without considering climate change, except for the two-layer capillary barrier cover (CBC) in Singapore (the service life is approximately 67 years). Under a changing climate, the mean service life of the CBC decreases to as low as 74 years in Shenzhen and 64 years in Singapore. In contrast, both the conventional clay-based four-layer cover and the sustainable three-layer cover incorporating recycled concrete aggregates remain resilient, maintaining 100-year serviceability across different climatic regions. Considering the service performance together with total cost and amount of carbon emissions, both estimated using a life cycle assessment framework, the sustainable three-layer cover is recommended. This is because it achieves the lowest cost and carbon footprint while sustaining a low failure probability under a changing climate.